Forward imaging catheter for intravascular ultrasound imaging and intravascular ultrasound imaging device

Abstract

The specification discloses a forward imaging catheter applied to intravascular ultrasound imaging and an intravascular ultrasound imaging device, and relates to the technical field of intravascular ultrasound imaging. In the forward imaging catheter, a detection optical fiber is arranged side by side with the excitation optical fiber, and a distal end of the detection optical fiber is provided with a back echo detection assembly having a detection surface for responding to an ultrasonic echo, the detection surface being arranged opposite to a distal end surface of the detection optical fiber for modulating detection light under the influence of the ultrasonic echo. A photoacoustic conversion film is arranged at the distal ends of the excitation optical fiber and the detection optical fiber. The photoacoustic conversion film and the back echo detection assembly form a transmitting-receiving configuration, at least part of the photoacoustic conversion film does not shield the detection surface, so that the ultrasonic echo reflected by a to-be-detected region returns along a forward direction and acts on the detection surface. It can be seen that, based on the back echo detection assembly arranged at the distal end surface of the detection optical fiber and the photoacoustic conversion film, forward ultrasonic detection is realized.

Description

Technical Field

[0001] This specification relates to the field of intravascular ultrasound imaging technology, and in particular to a forward imaging catheter and intravascular ultrasound imaging device for use in intravascular ultrasound imaging. Background Technology

[0002] Intravascular ultrasound imaging technology is extremely important in coronary interventional diagnosis and treatment, and is used to achieve real-time imaging of the internal structure and guidewire approach of chronic total occlusion lesions, and visualization of the distal vessel wall and plaque morphology in severely stenotic lesions.

[0003] In existing technologies, an ultra-miniature catheter is typically pushed along a guidewire to the target area of ​​the blood vessel. The ultrasound excitation / probe plane on the side of the catheter faces the lateral tissue, emitting broadband ultrasound waves and receiving forward echoes. The images on the side of the probe are then reconstructed and used to guide surgical instruments and optimize treatment decisions.

[0004] However, existing technologies make it difficult to achieve forward imaging, which leads to the risk of vascular dissection and perforation during blind guidewire puncture. Summary of the Invention

[0005] This specification provides a forward imaging catheter and an intravascular ultrasound imaging device for use in intravascular ultrasound imaging, to at least partially solve the aforementioned problems existing in the prior art.

[0006] The following technical solution is adopted in this specification: This specification provides a forward imaging catheter for intravascular ultrasound imaging, comprising: Excitation fiber, used to output excitation light; A probe fiber is arranged side by side with the excitation fiber. An echo detection component is provided at the distal end of the probe fiber. The echo detection component has a detection surface for responding to ultrasonic echoes. The detection surface is arranged opposite to the distal end face of the probe fiber and is configured to modulate the probe light incident along the probe fiber in response to the ultrasonic echo reflected from the area to be tested. A photoacoustic conversion membrane, disposed at the distal end of the excitation optical fiber and the probe optical fiber, is configured to convert the excitation light into ultrasonic waves through a photoacoustic effect and project them outward in the forward direction to the area to be measured. The photoacoustic conversion film and the echo detection component form a transmit-receive configuration, wherein at least a portion of the photoacoustic conversion film does not obstruct the detection surface, so that the ultrasonic echo reflected from the area under test returns along the forward direction and acts on the detection surface.

[0007] Preferably, the forward imaging catheter used for intravascular ultrasound imaging includes a lens; The lens is disposed at the distal end face of the excitation fiber and is used to shape the beam output from the distal end face of the excitation fiber.

[0008] Preferably, the forward imaging catheter used for intravascular ultrasound imaging includes a fixation element; The fixing member is closely attached to the excitation fiber and the detection fiber to fix the excitation fiber and the detection fiber.

[0009] Preferably, the photoacoustic conversion film has a centrally symmetric structure with a concave hemispherical shape; The axis of symmetry of the photoacoustic conversion film is approximately coincident with the optical axis of the excitation fiber or the detection fiber, and the first surface of the photoacoustic conversion film is a concave surface.

[0010] Preferably, the forward imaging catheter used for intravascular ultrasound imaging includes an elastic element and a protective tube; The elastic element is sleeved on the outside of the excitation optical fiber and the detection optical fiber, and is used for flexible support and torque transmission; The protective tube is sleeved on the outside of the elastic member, and the distal end face of the detection optical fiber passes through the protective tube and is exposed to the outside.

[0011] Preferably, the length of the probe fiber is greater than the length of the excitation fiber, such that the distal end of the probe fiber is closer to the distal end of the forward imaging catheter used for intravascular ultrasound imaging than the distal end of the excitation fiber. The photoacoustic conversion membrane is disposed only at the far end of the detection optical fiber.

[0012] Preferably, the distal end faces of the excitation fiber and the probe fiber are oriented toward the direction of advancement of the forward imaging conduit; The excitation fiber is used to emit excitation light in the direction of advancement of the forward imaging duct; The photoacoustic conversion membrane is used to convert the excitation light into a probe acoustic wave and emit the probe acoustic wave in the direction of advancement of the forward imaging conduit; The detection fiber is used to transmit detection light, which is affected by the ultrasonic echo returning from the area to be tested and transmitted back.

[0013] Preferably, the forward-facing all-optical ultrasound imaging catheter includes a drive mechanism; The drive device is connected to the forward imaging catheter and is configured to drive the distal end of the forward imaging catheter to rotate, move, retract, swing, or perform a combination of these movements, so that the catheter forms two-dimensional or three-dimensional ultrasound images in the forward direction.

[0014] Preferably, the driving device is provided with multiple smoothing rings, which are configured to receive incident excitation light and probe light, and transmit the excitation light and probe light to the excitation fiber and the probe fiber, respectively.

[0015] On the other hand, this specification provides an intravascular ultrasound imaging device, including the forward imaging catheter for intravascular ultrasound imaging provided in the foregoing aspect.

[0016] The above-mentioned technical solutions adopted in this specification can achieve the following beneficial effects: Based on the above, the forward imaging catheter used for intravascular ultrasound imaging includes an excitation fiber, a probe fiber, and a photoacoustic conversion membrane. The excitation fiber outputs excitation light. The probe fiber is arranged side-by-side with the excitation fiber. An echo detection component is located at the distal end of the probe fiber, and the echo detection component has a detection surface for responding to ultrasound echoes. The detection surface is positioned opposite the distal end face of the probe fiber and is configured to modulate the probe light incident along the probe fiber in response to the ultrasound echo reflected from the region to be measured. The photoacoustic conversion membrane is located at the distal ends of the excitation fiber and the probe fiber and is configured to convert the excitation light into ultrasound waves via a photoacoustic effect, and project them outwards in the forward direction to the region to be measured.

[0017] As can be seen, forward ultrasonic detection was achieved based on the echo detection component and photoacoustic conversion membrane set on the far end face of the detection fiber. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this specification and form part of this specification, illustrate exemplary embodiments and are used to explain this specification, but do not constitute an undue limitation thereof. In the drawings: Figure 1 A schematic diagram of the structure of a forward imaging catheter for intravascular ultrasound imaging provided as an embodiment of this specification; Figure 2 A schematic diagram of the structure of a forward imaging catheter for intravascular ultrasound imaging provided as an embodiment of this specification; Figure 3 A schematic diagram of the structure of a forward imaging catheter for intravascular ultrasound imaging provided as an embodiment of this specification; Figure 4 This is a schematic flowchart illustrating a method for fabricating a forward imaging catheter used in intravascular ultrasound imaging, as described in this specification.

[0019] Explanation of reference numerals in the attached figures: Excitation fiber 1; detection fiber 2; photoacoustic conversion membrane 3; fixing plate 4; elastic element 5; lens 6. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this specification clearer, the technical solutions of this specification will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or" unless otherwise expressly stated in the content.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Furthermore, in the description of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0023] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] The technical solutions provided in the various embodiments of this specification are described in detail below with reference to the accompanying drawings.

[0025] Figure 1 , Figure 2 as well as Figure 3 These are all schematic diagrams of the forward imaging catheter used for intravascular ultrasound imaging, provided as an embodiment of this specification. Figure 1 , Figure 2 as well as Figure 3 As shown, the forward imaging catheter used for intravascular ultrasound imaging includes an excitation fiber, a probe fiber, and a photoacoustic conversion membrane.

[0026] Preferably, the distal end face of the excitation fiber faces the forward extension direction of the excitation fiber.

[0027] Preferably, the excitation fiber is used to output excitation light.

[0028] Preferably, the distal end face of the excitation fiber is used to emit excitation light.

[0029] Preferably, the distal end face of the excitation fiber faces the direction of advancement of the forward imaging duct.

[0030] Preferably, the excitation fiber is used to emit excitation light in the direction of advancement of the forward imaging duct.

[0031] The direction in which the forward imaging catheter is advanced is the direction in which the forward imaging catheter moves during use.

[0032] Preferably, the excitation fiber is a multimode fiber.

[0033] Preferably, the excitation fiber has a core diameter of 105 μm and a numerical aperture of 0.22, and is used for low-loss transmission of high-power pulsed laser.

[0034] Preferably, the core diameter of the excitation fiber is 50-300 μm, such as 80 μm, 120 μm, 150 μm, 260 μm, etc. The numerical aperture of the excitation fiber is 0.1-0.36, such as 0.12, 0.15, 0.25, 0.28, 0.33, etc.

[0035] Preferably, the wavelength of the pulsed laser is 1064 nm and the pulse width is 5 ns. The wavelength of the pulsed laser can also be 800 nm, 532 nm, or any value within the range of 500 nm to 1500 nm, and this specification does not impose any restrictions on it.

[0036] Preferably, the detection fiber and the excitation fiber are arranged side by side and parallel to each other.

[0037] In one or more preferred embodiments provided in this specification, the probe fiber and the excitation fiber are coaxial. The forward imaging catheter for intravascular ultrasound imaging includes a wavelength division multiplexer, which enables the excitation and probe light to be transmitted in the same fiber, reducing the catheter's outer diameter and simplifying the packaging structure.

[0038] Preferably, an echo detection component is provided at the far end of the detection fiber.

[0039] Preferably, the echo detection component has a detection surface located at the far end face of the detection fiber.

[0040] Preferably, the echo detection component includes one or more of the following: a fiber Fabry-Pérot (FP) cavity, an end-face π-phase-shift fiber Bragg grating, an end-face diaphragm interference structure, an end-face microcavity structure, an end-face microring resonant structure, or an end-face MEMS optical detection structure.

[0041] Preferably, the echo detection component includes a π phase-shifted fiber Bragg grating.

[0042] More preferably, the π-phase shift point of the π-phase shift fiber Bragg grating is located at the far end face of the probe fiber. The echo detection assembly includes an FP cavity.

[0043] Preferably, an FP cavity is formed at the far end face of the probe fiber. The forward ultrasonic echo acts on the end face diaphragm or cavity reflective surface, causing a change in cavity length. The ultrasonic signal is read out by the change in interference spectrum.

[0044] Preferably, the fiber end-face microcavity / polymer microcavity detector is fabricated by preparing polymer microcavities, air-gap microcavities, femtosecond laser-processed microcavities, or thin-film microcavities on the fiber end face, and changing the cavity length, refractive index, or reflection conditions by forward acoustic pressure to achieve ultrasonic detection.

[0045] Preferably, the detection surface is positioned opposite to the far end face of the detection optical fiber.

[0046] Preferably, the probe surface is configured to modulate the probe light incident along the probe fiber in response to the ultrasonic echo reflected from the region to be measured.

[0047] More preferably, the echo detection component includes an end-face micro-ring resonant structure or an end-face micro-electro-mechanical-system (MEMS) optical detection structure disposed at the distal end face of the probe fiber. The end-face micro-ring resonant structure or the end-face MEMS optical detection structure is configured to generate changes in optical resonance characteristics in response to ultrasonic echoes returning in the forward direction, and to modulate the probe light incident along the probe fiber based on the changes in optical resonance characteristics.

[0048] Preferably, the probe fiber is provided with a π phase-shifted Bragg grating, and the distal end face of the probe fiber is the π phase-shift point of the π phase-shifted Bragg grating. That is, the probe fiber is inscribed with a π phase-shifted Bragg grating and is ground from the distal end until the distal end face is the π phase-shift point of the π phase-shifted Bragg grating.

[0049] Preferably, a reflective film is provided on the distal end face of the detection fiber. The reflective film and the π phase-shift Bragg grating together form an optical resonant cavity so that the incident detection light resonates in the optical resonant cavity. When external ultrasound acts on the distal end of the detection fiber, it causes a change in the effective optical path or resonant wavelength of the optical resonant cavity, thereby realizing ultrasonic detection through the change in reflected light intensity.

[0050] Preferably, the reflective film is a silver film, gold film, aluminum film, dielectric high-reflection film, etc., which obtains higher chemical stability and antioxidant performance, and is suitable for long-term implantation or more severe environments. This specification does not limit the specific reflective film used.

[0051] Preferably, the reflectivity of the reflective film is >90%.

[0052] Using the above methods, the distal end face of the probe fiber inscribed with a π-phase-shift Bragg grating is ground until it reaches the π-phase-shift point, and then coated with a highly reflective film. This enables the grating, which was originally only sensitive to lateral movements, to acquire high-sensitivity forward axial ultrasonic detection capabilities, achieving a forward imaging depth of ≥5mm and overcoming the limitations of lateral imaging. Furthermore, the reflective film acts as a distal reflector, allowing the truncated π-phase-shift Bragg grating to optically form an equivalent resonant cavity structure, thereby maintaining the narrowband resonance characteristics of the π-phase-shift Bragg grating. When external sound pressure is applied to the distal end face, it causes changes in the effective refractive index and / or effective optical path of the equivalent resonant cavity, leading to a shift in the resonant wavelength. Sound pressure detection is achieved by detecting changes in the reflected light intensity, and the noise equivalent sound pressure can reach the order of 10 Pa.

[0053] Preferably, the reflective film is a silver film, and the thickness of the silver film is 100-200nm, with a reflectivity >95%.

[0054] In a preferred embodiment, the probe fiber is provided with a π phase-shifted Bragg grating, and is polished so that its distal end face is the π phase-shift point of the π phase-shifted Bragg grating.

[0055] In a further preferred embodiment, a reflective film is disposed on the distal end face, and the reflective film and the π phase-shift Bragg grating together constitute an optical resonant cavity. The reflective film is a silver film with a thickness of 100-200 nm and a reflectivity greater than 95%. When external ultrasound acts on the distal end of the detection fiber, it causes a change in the effective optical path or resonant wavelength of the optical resonant cavity, and ultrasonic detection is achieved through changes in the reflected light intensity.

[0056] With the above structure, the silver mirror coating process is mature, low-cost and repeatable, which is conducive to the mass production of high-quality forward-facing intravascular ultrasound imaging probes.

[0057] Preferably, the photoacoustic conversion membrane is disposed at the distal end of the excitation fiber and the probe fiber.

[0058] Preferably, the distal ends of the excitation fiber and the probe fiber are not flush, and the distal end of the probe fiber extends further than the distal end of the excitation fiber. That is, when their proximal ends are flush, the length of the probe fiber is greater than the length of the excitation fiber. In this case, the photoacoustic conversion membrane is only disposed at the distal end of the probe fiber.

[0059] Preferably, the distal ends of the excitation fiber and the probe fiber are not flush, and the distal end of the excitation fiber extends further than the distal end of the probe fiber. That is, when their proximal ends are flush, the length of the probe fiber is less than the length of the excitation fiber. In this case, the photoacoustic conversion membrane is only disposed at the distal end of the excitation fiber.

[0060] Preferably, the distal end of the probe fiber is flush with the distal end of the excitation fiber, or the distal end of the probe fiber extends a certain distance from the distal end of the excitation fiber. In this case, the first surface of the photoacoustic conversion membrane faces the distal end face of the probe fiber, and the second surface of the photoacoustic conversion membrane faces the extension direction of the probe fiber, for converting optical signals into acoustic signals. That is, during use, the second surface of the photoacoustic conversion membrane faces the forward direction of the imaging guide tube to achieve forward detection.

[0061] like Figure 1 As shown, the distal end of the probe fiber extends a certain distance from the distal end of the excitation fiber. The first surface of the photoacoustic conversion film faces the distal end face of the probe fiber, and the second surface of the photoacoustic conversion film faces the extension direction of the probe fiber.

[0062] Preferably, the distal end face of the excitation fiber and the probe fiber faces the direction of advancement of the forward imaging conduit.

[0063] Preferably, the photoacoustic conversion film is used to convert the excitation light into a probe acoustic wave and emit the probe acoustic wave in the direction of advancement of the forward imaging conduit.

[0064] Preferably, the photoacoustic conversion membrane is disposed at the distal end of the excitation fiber and the probe fiber.

[0065] Preferably, the photoacoustic conversion membrane is configured to convert the excitation light into ultrasonic waves, i.e., the probe sound waves, through a photoacoustic effect and project them outward in the forward direction to the area to be measured.

[0066] Preferably, the photoacoustic conversion film and the echo detection component form a transmitting and receiving configuration. The related technologies for transmitting and receiving configurations are already relatively mature, and will not be described in detail here.

[0067] Preferably, at least a portion of the photoacoustic conversion film does not obstruct the detection surface, so that the ultrasonic echo reflected from the area under test returns in the forward direction and acts on the detection surface.

[0068] Preferably, the probe fiber is used to transmit probe light, which is affected by the ultrasonic echo returning from the area to be tested and transmitted back.

[0069] In a further preferred embodiment, where the distal ends of the probe fiber and the excitation fiber are flush, a photoacoustic conversion film is disposed at the distal ends of both the excitation fiber and the probe fiber. A first surface of the photoacoustic conversion film faces the distal end face of the probe fiber, and a second surface faces the extending direction of the probe fiber, for converting optical signals into acoustic signals. In the above-described transmit-receive configuration, at least a portion of the photoacoustic conversion film does not obstruct the probe surface, allowing the ultrasonic echo reflected from the area under test to return in the forward direction and act on the probe surface to modulate the probe light incident along the probe fiber.

[0070] Based on the above, the forward imaging catheter used for intravascular ultrasound imaging includes an excitation fiber, a probe fiber, and a photoacoustic conversion membrane. The probe fiber is arranged side-by-side with the excitation fiber, and an echo detection component is disposed at the distal end of the probe fiber. The echo detection component has a detection surface for responding to ultrasound echoes, which is positioned opposite to the distal end face of the probe fiber and configured to modulate the probe light incident along the probe fiber in response to the ultrasound echo reflected from the region under test. The photoacoustic conversion membrane is disposed at the distal ends of the excitation and probe fibers and is configured to convert the excitation light into ultrasound waves via a photoacoustic effect, and project them outward in the forward direction to the region under test. The photoacoustic conversion membrane and the echo detection component form a transmit-receive configuration, with at least a portion of the photoacoustic conversion membrane not obstructing the probe surface, so that the ultrasound echo reflected from the region under test returns in the forward direction and acts on the probe surface.

[0071] As can be seen, forward ultrasonic detection was achieved based on the echo detection component and photoacoustic conversion membrane set on the far end face of the detection fiber.

[0072] Furthermore, it employs an all-fiber structure, contains no metal wires or electrical transducers, is naturally compatible with Magnetic Resonance Imaging (MRI), and can be manufactured into an ultra-small probe with an outer diameter of <1mm (typically 0.9mm), enabling it to pass through vascular segments with severe stenosis and chronic total occlusion (CTO).

[0073] Preferably, the forward imaging catheter used for intravascular ultrasound imaging is an all-optical structure, that is, an all-optical forward imaging catheter used for intravascular ultrasound imaging.

[0074] Preferably, the forward imaging catheter used for intravascular ultrasound imaging includes a lens.

[0075] Preferably, the lens is disposed at the distal end face of the excitation fiber to shape the beam output from the distal end face of the excitation fiber.

[0076] like Figure 1 as well as Figure 2 As shown, the lens is positioned at the distal end face of the excitation fiber.

[0077] Preferably, the lens is a gradient refractive index lens.

[0078] Preferably, the lens is a spherical lens, an aspherical lens, a cylindrical lens, a fused conical lens, etc., but this specification does not impose any restrictions.

[0079] Preferably, the lens is disposed between the distal end face of the excitation fiber and the photoacoustic conversion film, and is used to collimate, converge and shape the beam output from the distal end face of the excitation fiber, reduce beam divergence, increase energy density and improve excitation efficiency.

[0080] Preferably, the lens is used to directionally couple the probe light output from the fiber core, thereby improving the signal-to-noise ratio and detection efficiency.

[0081] In one or more preferred embodiments provided in this specification, a lens is disposed between the distal end face of the excitation fiber and the photoacoustic conversion film, and may be a gradient refractive index lens, a spherical lens, an aspherical lens, a cylindrical lens, or a fused conical lens, etc. The lens is used to collimate, converge, and shape the beam output from the distal end face of the excitation fiber to reduce beam divergence and improve energy density and excitation efficiency.

[0082] Preferably, the forward imaging catheter used for intravascular ultrasound imaging includes a fixation element.

[0083] Preferably, the fastener is closely attached to the excitation fiber and the probe fiber to fix the excitation fiber and the probe fiber.

[0084] Preferably, the fastener includes multiple fastener plates, at least one of which is used to fasten the excitation fiber and / or the probe fiber and / or the lens.

[0085] Preferably, the fixing member includes a connecting adhesive, and the fixing plate is provided with a through hole, within which the excitation fiber and the probe fiber are fitted. The gap between the through hole and the excitation fiber and the probe fiber is filled with the connecting adhesive.

[0086] Preferably, the adhesive is a biocompatible UV-curable optical adhesive that firmly bonds the excitation fiber and the probe fiber, preventing displacement and keeping the optical interface clean.

[0087] like Figure 1 as well as Figure 2 As shown, multiple fixing plates respectively fix the excitation fiber and the probe fiber.

[0088] In one or more preferred embodiments provided in this specification, the fixing member includes a plurality of fixing plates and a bonding adhesive, wherein at least one fixing plate is used to fix the excitation fiber and / or the probe fiber and / or the lens. The fixing plate is provided with a through hole, and the excitation fiber and the probe fiber are sleeved in the through hole. The gap between the through hole and the excitation fiber and the probe fiber is filled with bonding adhesive; the bonding adhesive may be a biocompatible UV-curable optical adhesive.

[0089] Preferably, the photoacoustic conversion membrane has a centrally symmetric structure with a concave hemispherical shape.

[0090] Preferably, the axis of symmetry of the photoacoustic conversion film is approximately coincident with the optical axis of the excitation fiber or the probe fiber, and the first surface of the photoacoustic conversion film is a concave surface.

[0091] Preferably, the first surface of the photoacoustic conversion film is a continuous concave surface.

[0092] Preferably, the concave surface faces the distal end face of the probe fiber and is away from the extension direction of the probe fiber.

[0093] like Figure 1 as well as Figure 2 As shown, the concave surface faces the distal end face of the probe fiber and is away from the extension direction of the probe fiber, that is, away from the tissue inside the patient's body. The concave surface, i.e. Figure 1 as well as Figure 2 The concave side of the hemispherical photoacoustic conversion membrane 3.

[0094] Preferably, the photoacoustic conversion film includes a curved substrate and a conversion layer.

[0095] Preferably, the curved substrate is made of a transparent material, such as quartz, glass, sapphire, or polymethyl methacrylate.

[0096] Preferably, the concave surface is a sphere, parabola, ellipsoid, or other freeform surface, which is not limited herein.

[0097] Preferably, the conversion layer includes a light absorption layer and / or a photothermal conversion layer.

[0098] Preferably, the conversion layer is a carbon nanotube / polymer composite film, graphene / polydimethylsiloxane composite film, or gold nanoparticle / polydimethylsiloxane composite film deposited on the concave surface of the concave surface, etc., which is not limited in this specification.

[0099] Preferably, the conversion layer is a carbon nanotube / polymer composite film, a graphene / polydimethylsiloxane composite film, or a gold nanoparticle / polydimethylsiloxane composite film deposited on the curved substrate, etc., and this specification does not impose any restrictions.

[0100] Preferably, the conversion layer is a high-light-absorbing composite material such as a multi-walled carbon nanotube-polymethyl methacrylate composite film, a carbon nanotube / polymer composite film, a graphene / polydimethylsiloxane composite film, a gold nanoparticle / polydimethylsiloxane composite film, or a melanin / polydimethylsiloxane composite film. This allows for matching different excitation wavelengths and further improves photoacoustic conversion efficiency or biocompatibility. The specific material of the conversion layer is not limited herein. Furthermore, the wavelength, pulse width, and other parameters of the laser transmitted within the excitation and probe fibers are also adapted to the absorption peaks of the photoacoustic conversion film to improve energy coupling efficiency.

[0101] Using the above method, combined with broadband photoacoustic excitation of multi-walled carbon nanotube-polymethyl methacrylate composite film, the probe bandwidth is >50MHz and the axial resolution is <30μm, which is far superior to the miniaturized piezoelectric transducer (bandwidth <30MHz).

[0102] Preferably, the thickness of the conversion layer is 10~50μm.

[0103] Preferably, the thickness of the conversion layer is 5-500μm, such as 20μm, 30μm, 45μm, 80μm, 100μm, 150μm, 180μm, 230μm, 360μm, 450μm, etc.

[0104] Preferably, the conversion layer includes a protective layer, an acoustic matching layer, and / or a back reflective layer.

[0105] In one or more preferred embodiments provided in this specification, the photoacoustic conversion film includes a curved substrate and a conversion layer. The curved substrate is a transparent material, such as quartz, glass, sapphire, or polymethyl methacrylate. The first surface of the photoacoustic conversion film is concave, which can be a sphere, parabola, ellipsoid, or freeform surface. The conversion layer includes a light absorption layer and / or a photothermal conversion layer, and the thickness of the conversion layer can be 10–50 μm.

[0106] Preferably, the forward imaging catheter used for intravascular ultrasound imaging includes an elastic element and a protective tube.

[0107] Preferably, the elastic element is sleeved on the outside of the excitation optical fiber and the detection optical fiber for flexible support and torque transmission.

[0108] Preferably, the protective tube is sleeved on the outside of the protective tube, and the distal end face of the detection optical fiber passes through the protective tube and is exposed to the outside.

[0109] Preferably, the elastic element is a torsion spring.

[0110] Preferably, the elastic element is used to provide flexible support and excellent torsional resistance, ensuring 1:1 torque transmission, while avoiding fiber optic bending damage, and improving the handling feel and reliability of the push.

[0111] Preferably, the elastic element is a metal woven mesh.

[0112] like Figure 3 As shown, the elastic element is a metal woven mesh.

[0113] In one or more preferred embodiments provided in this specification, an elastic element is sleeved on the outside of the excitation fiber and the probe fiber for flexible support and torque transmission; a protective tube is sleeved on the outside of the elastic element, and the distal end face of the probe fiber passes through the protective tube and is exposed. The elastic element may be a torsion spring or a metal braided mesh.

[0114] Preferably, the length of the probe fiber is greater than the length of the excitation fiber, such that the distal end of the probe fiber is closer to the distal end of the forward imaging catheter used for intravascular ultrasound imaging than the distal end of the excitation fiber.

[0115] Preferably, the photoacoustic conversion membrane is disposed only at the far end of the detection optical fiber.

[0116] In one or more preferred embodiments provided in this specification, the proximal end is flush and the length of the probe fiber is greater than the length of the excitation fiber. The distal end of the probe fiber extends forward relative to the distal end of the excitation fiber, and the photoacoustic conversion membrane is disposed only at the distal end of the probe fiber. After the pulsed laser is transmitted through the excitation fiber, it is shaped by a lens and irradiates the multi-walled carbon nanotube / polymethyl methacrylate composite film of the photoacoustic conversion membrane. The multi-walled carbon nanotubes absorb the light energy and heat up instantaneously, while the polymethyl methacrylate undergoes thermoelastic expansion, thereby radiating forward ultrasonic waves.

[0117] Preferably, after being transmitted through an excitation fiber, the pulsed laser is shaped by a lens and irradiates the multi-walled carbon nanotube / polymethyl methacrylate composite film. The multi-walled carbon nanotubes absorb the light energy and heat up instantaneously, causing the polymethyl methacrylate to undergo thermoelastic expansion, thereby radiating broadband forward ultrasonic waves with a bandwidth greater than 50 MHz.

[0118] In a further preferred embodiment, forward ultrasound waves act on the patient's tissue in front of the probe. The echoes generated by the scattering or reflection of the tissue return perpendicularly to the probe along the fiber optic axis and reach the distal end face where the silver film is located. The silver film, acting as both an optical reflection interface and an acoustic pressure stress interface, forms a transient acoustic pressure load under the influence of the echo acoustic pressure. This acoustic pressure load causes minute mechanical vibrations, strains, or refractive index disturbances in the silver film and the distal end of the connected probe fiber, which couple to the FP-type optical resonant cavity formed by the silver film and a ground and shortened π-phase-shift fiber Bragg grating. This causes slight perturbations in the effective optical path and / or effective refractive index of the resonant cavity, resulting in a shift in the narrowband resonant wavelength or the position of the resonant valley of the FP-type optical resonant cavity. The narrow-linewidth probe laser operates at the edge of the narrowband resonant valley or in the region of the reflection spectrum slope. Utilizing the edge filtering effect, the resonant wavelength shift is converted into a linear change in transmitted and / or reflected light intensity. This intensity change is received and acquired by a high-speed photodetector, and after signal processing, a forward image of the blood vessel wall structure and plaque interface in front of the probe is reconstructed.

[0119] In one or more preferred imaging embodiments provided in this specification, a forward imaging conduit is connected to a driving device, which is configured to drive the distal end of the forward imaging conduit to rotate, move, retract, oscillate, or perform a combination of such movements, so that the conduit forms two-dimensional or three-dimensional ultrasound images along the forward direction. The driving device contains multiple smoothing rings configured to receive incident excitation and probe light, and to transmit the excitation and probe light to the excitation and probe optical fibers, respectively.

[0120] The above are one or more embodiments of the forward imaging catheter for intravascular ultrasound imaging provided in this specification. Based on the same idea, this specification also provides a method for fabricating a corresponding forward imaging catheter for intravascular ultrasound imaging. Figure 4 This is a schematic flowchart illustrating a method for fabricating a forward imaging catheter used in intravascular ultrasound imaging, as described in this specification. Figure 4 As shown, the specific steps include: S900: A π phase-shifted Bragg grating is written into a single-mode fiber.

[0121] S902: Grind the far end of the single-mode fiber until the π phase shift point is located at the far end face of the single-mode fiber.

[0122] Preferably, during grinding, a progressively finer grinding plate is used, and the transmission spectrum is monitored in real time until the π phase shift point is reached.

[0123] S904: Clean and activate the far end face of the single-mode fiber.

[0124] Preferably, the distal end face of the single-mode optical fiber is cleaned by ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water in sequence, followed by activation with dilute hydrochloric acid.

[0125] S906: A reflective film is deposited on the far end face of the single-mode optical fiber using a target solution and a reducing agent to form a probe fiber.

[0126] Preferably, the target solution contains metal ions that can be deposited onto the far end face of the single-mode optical fiber under the action of a reducing agent.

[0127] Preferably, a silver ammonia solution is mixed with a glucose (or formaldehyde) reducing agent, and the distal end face of the single-mode optical fiber is immersed in the reaction for 3-5 minutes to deposit a dense silver film of 100-200 nm. The reflectance spectrum is then detected to confirm the recovery of the transmission valley characteristics (linewidth < 5 μm); if this fails, the process is repeated.

[0128] S908: A photoacoustic conversion membrane is provided on the distal end face of the excitation optical fiber, wherein the first side of the photoacoustic conversion membrane faces the distal end face of the excitation optical fiber, and the second side of the photoacoustic conversion membrane faces the extension direction of the excitation optical fiber.

[0129] Preferably, multi-walled carbon nanotubes are ultrasonically dispersed in a polymethyl methacrylate / toluene solution, spin-coated onto a silver-plated end face or a substrate tightly adhered to the end face, and then dried to form a film.

[0130] S910: Fix the excitation fiber and the detection fiber so that the excitation fiber and the detection fiber are side by side and parallel.

[0131] Preferably, the excitation fiber with lens and the processed detection fiber are placed into the fixing plate, glue is injected and cured through the dispensing hole, a protective tube is inserted and a torsion spring is assembled to ensure that the photoacoustic conversion film and the sensitive area of ​​the π phase-shift Bragg grating are located on the same plane at the front end.

[0132] Preferably, in step S910, the excitation fiber and the probe fiber can be fixed by a fixing plate. The fixing plate has a through hole. Connecting adhesive is injected through the through hole of the fixing plate to fix the excitation fiber and the probe fiber.

[0133] The above are one or more embodiments of the forward imaging catheter for intravascular ultrasound imaging and the method for manufacturing the forward imaging catheter for intravascular ultrasound imaging provided in this specification. Based on the same idea, this specification also provides corresponding intravascular ultrasound imaging equipment.

[0134] Preferably, the intravascular ultrasound imaging device includes the forward imaging catheter for intravascular ultrasound imaging provided in any of the above embodiments.

[0135] Preferably, when the intravascular ultrasound imaging device is working, the pulsed laser is transmitted through the excitation fiber and shaped by the lens before acting on the photoacoustic conversion membrane to generate forward ultrasound waves; the forward ultrasound waves are reflected by the area to be tested to form ultrasound echoes, and the ultrasound echoes act on the echo detection component at the far end of the probe fiber to modulate the probe light. The changes in light intensity are received and collected by the high-speed photodetector, and the forward image in front of the probe is reconstructed after signal processing.

[0136] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0137] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the embodiment on the method for fabricating a forward imaging catheter for intravascular ultrasound imaging is described simply because it corresponds to the embodiment on a forward imaging catheter for intravascular ultrasound imaging; relevant parts can be referred to mutually.

[0138] The above description is merely an embodiment of this specification and is not intended to limit this specification. Various modifications and variations can be made to this specification by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of the claims of this application.

[0139] It should be noted that all actions involving the acquisition of signals, information, or data in this application are carried out in compliance with the relevant data protection laws and policies of the country where the application is located, and with the authorization granted by the owner of the relevant device.

[0140] In the 1990s, improvements to a technology could be clearly distinguished as either hardware improvements (e.g., improvements to the circuit structure of diodes, transistors, switches, etc.) or software improvements (improvements to the methodology). However, with technological advancements, many methodological improvements today can be considered direct improvements to the hardware circuit structure. Designers almost always obtain the corresponding hardware circuit structure by programming the improved methodology into the hardware circuit. Therefore, it cannot be said that a methodological improvement cannot be implemented using hardware physical modules. For example, a Programmable Logic Device (PLD) (such as a Field Programmable Gate Array (FPGA)) is such an integrated circuit whose logic function is determined by the user programming the device. Designers can program and "integrate" a digital system onto a PLD themselves, without needing chip manufacturers to design and manufacture dedicated integrated circuit chips. Furthermore, nowadays, instead of manually manufacturing integrated circuit chips, this programming is mostly implemented using "logic compiler" software. Similar to the software compiler used in program development, the original code before compilation must also be written in a specific programming language, called a Hardware Description Language (HDL). There are many HDLs, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, and RHDL (Ruby Hardware Description Language). Currently, the most commonly used are VHDL (Very-High-Speed ​​Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also understand that by simply performing some logic programming on the method flow using one of these hardware description languages ​​and programming it into an integrated circuit, the hardware circuit implementing the logical method flow can be easily obtained.

[0141] The controller can be implemented in any suitable manner. For example, it can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicon Labs C8051F320. A memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art will also recognize that, in addition to implementing the controller in purely computer-readable program code form, the same functionality can be achieved by logically programming the method steps to make the controller take the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the means included therein for implementing various functions can also be considered as structures within the hardware component. Alternatively, the means for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0142] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0143] For ease of description, the above devices are described in terms of function, divided into various units. Of course, in implementing this specification, the functions of each unit can be implemented in one or more software and / or hardware components.

[0144] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0145] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0146] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0147] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0148] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0149] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0150] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0151] Those skilled in the art will understand that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, this specification may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this specification may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0152] This specification can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This specification can also be practiced in distributed computing environments, where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

Claims

1. A forward imaging catheter for intravascular ultrasound imaging, characterized in that, include: Excitation fiber, used to output excitation light; A probe fiber is arranged side by side with the excitation fiber. An echo detection component is provided at the distal end of the probe fiber. The echo detection component has a detection surface for responding to ultrasonic echoes. The detection surface is arranged opposite to the distal end face of the probe fiber and is configured to modulate the probe light incident along the probe fiber in response to the ultrasonic echo reflected from the area to be tested. A photoacoustic conversion membrane, disposed at the distal end of the excitation optical fiber and the probe optical fiber, is configured to convert the excitation light into ultrasonic waves through a photoacoustic effect and project them outward in the forward direction to the area to be measured. The photoacoustic conversion film and the echo detection component form a transmit-receive configuration, wherein at least a portion of the photoacoustic conversion film does not obstruct the detection surface, so that the ultrasonic echo reflected from the area under test returns along the forward direction and acts on the detection surface.

2. The forward imaging catheter for intravascular ultrasound imaging according to claim 1, characterized in that, The forward imaging catheter used for intravascular ultrasound imaging includes a lens; The lens is disposed at the distal end face of the excitation fiber and is used to shape the beam output from the distal end face of the excitation fiber.

3. The forward imaging catheter for intravascular ultrasound imaging according to claim 1, characterized in that, The forward imaging catheter used for intravascular ultrasound imaging includes a fixation element; The fixing member is closely attached to the excitation fiber and the detection fiber to fix the excitation fiber and the detection fiber.

4. The forward imaging catheter for intravascular ultrasound imaging according to claim 1, characterized in that, The photoacoustic conversion membrane has a centrally symmetrical structure with a concave hemispherical shape; The axis of symmetry of the photoacoustic conversion film is approximately coincident with the optical axis of the excitation fiber or the detection fiber, and the first surface of the photoacoustic conversion film is a concave surface.

5. The forward imaging catheter for intravascular ultrasound imaging according to claim 1, characterized in that, The forward imaging catheter used for intravascular ultrasound imaging includes an elastic element and a protective tube; The elastic element is sleeved on the outside of the excitation optical fiber and the detection optical fiber, and is used for flexible support and torque transmission; The protective tube is sleeved on the outside of the elastic member, and the distal end face of the detection optical fiber passes through the protective tube and is exposed to the outside.

6. The forward imaging catheter for intravascular ultrasound imaging according to any one of claims 1-5, characterized in that, The length of the probe fiber is greater than the length of the excitation fiber, such that the distal end of the probe fiber is closer to the distal end of the forward imaging catheter used for intravascular ultrasound imaging than the distal end of the excitation fiber. The photoacoustic conversion membrane is disposed only at the far end of the detection optical fiber.

7. The forward imaging catheter for intravascular ultrasound imaging according to any one of claims 1-5, characterized in that, The distal end faces of the excitation fiber and the probe fiber are oriented toward the direction of advancement of the forward imaging conduit; The excitation fiber is used to emit excitation light in the direction of advancement of the forward imaging duct; The photoacoustic conversion membrane is used to convert the excitation light into a probe acoustic wave and emit the probe acoustic wave in the direction of advancement of the forward imaging conduit; The detection fiber is used to transmit detection light, which is affected by the ultrasonic echo returning from the area to be tested and transmitted back.

8. The forward imaging catheter for intravascular ultrasound imaging according to any one of claims 1-5, characterized in that, The forward-facing all-optical ultrasound imaging catheter includes a drive mechanism; The drive device is connected to the forward imaging catheter and is configured to drive the distal end of the forward imaging catheter to rotate, move, retract, swing, or perform a combination of these movements, so that the catheter forms two-dimensional or three-dimensional ultrasound images in the forward direction.

9. The forward imaging catheter for intravascular ultrasound imaging according to claim 8, characterized in that, The driving device is provided with multiple smoothing rings, which are configured to receive incident excitation light and probe light, and transmit the excitation light and probe light to the excitation fiber and the probe fiber, respectively.

10. An intravascular ultrasound imaging device, characterized in that, The forward imaging catheter for intravascular ultrasound imaging as described in any one of claims 1-9.

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